Recovering silver from Aluminum/silver chloride mud

[bhilton]

I have been saving all my gold recovery waste mud from processing mixed jeweler material that contains aluminum oxide sand paper in it and other dust from likely steel files and little steel saw blades.

Each time I process the material with AR, I end up with a bunch of this grey/white crystal mud which I believe is mostly aluminum and silver chlorides.

What is the best way to separate just the silver chloride using acids/chemicals?

Thank you!

Bill

 

[andu]

silver chloride stays as a milky substance that makes filtering difficult, but you can get rid of most the liquid then let it filtrate / use vacuum . aluminium should stay in solution as long as acidic. You should get rid of aluminium with hcl first, before AR.

 

[Yggdrasil]

I have been saving all my gold recovery waste mud from processing mixed jeweler material that contains aluminum oxide sand paper in it and other dust from likely steel files and little steel saw blades.

Each time I process the material with AR, I end up with a bunch of this grey/white crystal mud which I believe is mostly aluminum and silver chlorides.

What is the best way to separate just the silver chloride using acids/chemicals?

Thank you!

Bill

Aluminum oxide do not dissolve in acids we recommend to use.
So filtering is the only way.
As @andu said a good soak in HCl before dissolving anything precious will take care of any Tin Iron and such before dissolving the Gold.
If there is suspected to be Silver one might roast it after the HCl and then use Nitric to remove the Silver.

 

[anachronism]

Aluminum oxide do not dissolve in acids we recommend to use.
So filtering is the only way.
As @andu said a good soak in HCl before dissolving anything precious will take care of any Tin Iron and such before dissolving the Gold.
If there is suspected to be Silver one might roast it after the HCl and then use Nitric to remove the Silver.

Ygg, both Phosphoric and Citric acid will dissolve the Aluminium Oxide. I'm unsure without looking as to what affect they have on the Silver Chloride though.

Edit for typo

 

[Yggdrasil]

Ygg, both Phosphoric and Citric acid will dissolve the Aluminium Oxide. I'm unsure without looking as to what affect they have on the Silver Chloride though.

Edit for typo

I was of the impression you had do use some serious acids for that.
So I learned something new today

By the way I found it is also soluble in HCl as well so he can just use that.

 

[Yggdrasil]

After doing some research it seems that crystalline compact Aluminium oxide (Corundum) is insoluble in all but HF, molten NaOH and molten Cryolite.
Which is the type used for sandpapers and such.
It is soluble in melts containing Cryolite which is used in the production of Aluminum.
There are non crystalline Aluminum Oxides that is soluble in acids.
Have anyone tried to dissolve it?

 

[anarxi]

I have been saving all my gold recovery waste mud from processing mixed jeweler material that contains aluminum oxide sand paper in it and other dust from likely steel files and little steel saw blades.

Each time I process the material with AR, I end up with a bunch of this grey/white crystal mud which I believe is mostly aluminum and silver chlorides.

What is the best way to separate just the silver chloride using acids/chemicals?

Thank you!

Bill

try adding pure aluminum
for example, the body of an electrolytic capacitor.
if silver chloride is present there, it will turn gray (solution).
then get rid of excess moisture and melt what you got.
then redissolve in nitric acid and cement with copper.

 

[bhilton]

silver chloride stays as a milky substance that makes filtering difficult, but you can get rid of most the liquid then let it filtrate / use vacuum . aluminium should stay in solution as long as acidic. You should get rid of aluminium with hcl first, before AR.

Ok, my jeweler has been melting all his shop catch tray material into blobs of mixed gold, filings, sand paper aluminum oxides, etc. and rolling it into strips for me.

As I have been learning how to refine the gold, I have now asked him to leave the material in the dust form, avoid the time melting and rolling strips. The next batch he gives me I will boil the filings in hcl first. Then filter out the solution which will have dissolved the aluminum oxide? I presume it will dissolve small amounts of nickel, copper, etc.

Would you incinerate the dust first?

 

[andu]

I tend to avoid carbon production unless imperative, if whatever you have is insoluble you'll burn it whenever you burn the filterpaper anyway. Burning can induce loss of material if utmost care is not used.

 

[anarxi]

burning it won't do anything
Aluminum oxide is refractory, it will still remain in the ash...

 

[bhilton]

try adding pure aluminum
for example, the body of an electrolytic capacitor.
if silver chloride is present there, it will turn gray (solution).
then get rid of excess moisture and melt what you got.
then redissolve in nitric acid and cement with copper.

Ok, so my silver chloride is going to be precipitated and some still dissolved in solution, all mixed in with aluminum oxide corundum.

If I use pure aluminum to precipitate dissolved silver chloride to silver, that would still leave the non dissolved silver chloride in the currently gray milky gritty mud? If I proceed to melt, I would be melting silver chloride crystals, aluminum oxide and the precipitated silver together?

 

[Yggdrasil]

Ok, so my silver chloride is going to be precipitated and some still dissolved in solution, all mixed in with aluminum oxide corundum.

If I use pure aluminum to precipitate dissolved silver chloride to silver, that would still leave the non dissolved silver chloride in the currently gray milky gritty mud? If I proceed to melt, I would be melting silver chloride crystals, aluminum oxide and the precipitated silver together?

Silver Chloride is not going to be in solution and as such will not precipitate with Aluminum or other substances.
The only way to get out what is there is filtering it cold.
Hot strong AR can hold a bit of Silver Chloride just enough that it is a impurity for the refined Gold

Since this is Jewelers scrap, there is a likelihood that there is Tin in there
and then it is also likely that what you have is Metastannic acid.
It is hard to filter.
This creates a catch 22 situation.
Metastannic acid need to be dried and roasted, then dissolved in HCl
Silver Chloride need to be kept wet and converted by Lye/Sugar or Sulfuric/Iron or Zinc
How much Silver Chloride are we talking about?
It might be beneficial to just forget about the Silver Chloride this time.
Filter the solution and dry what is in the filter, then roast it until glowing a dull red for some time while stirring it.
Then dissolve what can be dissolved in HCl.
And you are ready to try again.

In retrospect the first thing you need to do next time with sweeps/mud is to roast it thoroughly then dissolve all that can in HCl.
This will get rid of Tin and Iron.

 

[bhilton]

Silver Chloride is not going to be in solution and as such will not precipitate with Aluminum or other substances.
The only way to get out what is there is filtering it cold.
Hot strong AR can hold a bit of Silver Chloride just enough that it is a impurity for the refined Gold

Since this is Jewelers scrap, there is a likelihood that there is Tin in there
and then it is also likely that what you have is Metastannic acid.
It is hard to filter.
This creates a catch 22 situation.
Metastannic acid need to be dried and roasted, then dissolved in HCl
Silver Chloride need to be kept wet and converted by Lye/Sugar or Sulfuric/Iron or Zinc
How much Silver Chloride are we talking about?
It might be beneficial to just forget about the Silver Chloride this time.
Filter the solution and dry what is in the filter, then roast it until glowing a dull red for some time while stirring it.
Then dissolve what can be dissolved in HCl.
And you are ready to try again.

In retrospect the first thing you need to do next time with sweeps/mud is to roast it thoroughly then dissolve all that can in HCl.
This will get rid of Tin and Iron.

I have already retrieved most of the gold and put in extra water and chilled the AR to drop any dissolved silver chloride crystals. Ive kept that clean silver chloride in its own stock pot.

The original left over grey silty mud from each first AR filtering might have tiny amounts of gold but I am wanting to fetch the silver. The mud came from approx 225g of 12k gold that my jeweler melted from all his catch tray dust into strips. There should not be much tin, but there will be some iron from his files.

How much silver could be in half that 225g? Maybe half of the 112.5, because they work on a lot of white gold. As a guess, 50g silver.

You are saying abandon the silver?

 

[Yggdrasil]

I have already retrieved most of the gold and put in extra water and chilled the AR to drop any dissolved silver chloride crystals. Ive kept that clean silver chloride in its own stock pot.

The original left over grey silty mud from each first AR filtering might have tiny amounts of gold but I am wanting to fetch the silver. The mud came from approx 225g of 12k gold that my jeweler melted from all his catch tray dust into strips. There should not be much tin, but there will be some iron from his files.

How much silver could be in half that 225g? Maybe half of the 112.5, because they work on a lot of white gold. As a guess, 50g silver.

You are saying abandon the silver?

No, I replied with respect to the murky liquid you have.
The idea that if it was not much, you could just let it slip by.
The Silver Chloride you have separated out is how much?
How much murky liquid do you have?

 

[bhilton]

No, I replied with respect to the murky liquid you have.
The idea that if it was not much, you could just let it slip by.
The Silver Chloride you have separated out is how much?
How much murky liquid do you have?

The murky mud is the remains of 225g of 12k gold strips, after dissolving them first with AR.

 

[Yggdrasil]

The murky mud is the remains of 225g of 12k gold strips, after dissolving them first with AR.

That is one question answered, how much Silver Chloride do you have?

 

[anarxi]

I have already retrieved most of the gold and put in extra water and chilled the AR to drop any dissolved silver chloride crystals. Ive kept that clean silver chloride in its own stock pot.

The original left over grey silty mud from each first AR filtering might have tiny amounts of gold but I am wanting to fetch the silver. The mud came from approx 225g of 12k gold that my jeweler melted from all his catch tray dust into strips. There should not be much tin, but there will be some iron from his files.

How much silver could be in half that 225g? Maybe half of the 112.5, because they work on a lot of white gold. As a guess, 50g silver.

You are saying abandon the silver?

White gold is an alloy of gold and palladium (84/16 classic), or gold and nickel.

 

[anarxi]

Try letting the solution sit for several days
Then, without touching the vessel, remove the top clean water.
Pour boiling water over the slurry.When exposed to boiling water, silver chloride turns into lumps.

 

[anarxi]

You can also dissolve silver chloride with an aqueous solution of ammonia.
and then precipitate it with hydrazine or ascorbic acid....


but they write that this is quite dangerous due to the possibility of creating “explosive” silver....

 

[bhilton]

That is one question answered, how much Silver Chloride do you have?

Very little, the last two gold drops, I had a thin layer of the white crystals covering the bottom of the beaker after I added water and chilled with ice. I filtered them and Im storing them in a wet stock pot of only those two filters so far.